The need to dispense particles in known amounts arises in a variety of procedures. Biological cells are examples of particles that often require dispensing in known amounts. Accurate and consistent dispensing of biological cells is important in the field of biomicrofluidics notably in mass and energy transport studies, and particularly in automated microfluidic devices, as well as in morphological studies and the long-term monitoring of cells. Dispensing equipment currently available is typically designed to dispense a given volume of liquid such as a cell suspension, but the number of cells in the dispensed volume is subject to variation due to such factors as adherence of the cells to each other, and disintegration, clumping, coagulation, and even mutation of the cells. Moreover, liquid-measuring dispensing methods are particularly unreliable in terms of cell count when the number of cells to be dispensed is small, such as less than 100. The most widely used dispensing devices are air displacement pipettes, which are micropipettes operated by air-driven pistons. These deliver accurate quantities of a liquid suspension in small volumes, but the number of cells in the delivered volume is still variable and uncertain. Other devices are those employing robotics for selecting and transporting individual cells. An example is the “CellBot” system of CSEM Microfluidics (Newchatel, Switzerland). Systems of this type require individual identification and transport of each cell. Still other devices dispense known amounts of droplets. An example is the JP D300 Digital Dispenser of Tecan Systems, Inc. (San Jose, Calif., USA). This type of system does not control actual cell counts, however.